An elevation of privilege vulnerability exists in the way that the Windows Network File System (NFS) handles objects in memory. An attacker who successfully exploited the vulnerability could execute code with elevated permissions. To exploit the vulnerability, a locally authenticated attacker could run a specially crafted application. The security update addresses the vulnerability by ensuring the Windows NFS properly handles objects in memory.
https://www.tenable.com/blog/tenable-roundup-for-microsofts-june-2019-patch-tuesday
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1045
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2019-1045